Virtual Elements

Virtual elements are created whenever a CSS requires an element to be rendered but must not pollute the DOM. Importantly, virtual elements are ordered. For example, the virtual element created by ::after shows up after the 'real' element has been drawn. PowerUI handles this by storing all virtual elements in a SortedDictionary, indexed by that priority value.

Accessing the virtual element set

There's a web API for doing this - specifically the element.getComputedStyle("after") method, which is supported. The set itself is:

// Get the virtuals set for 'element' (A HtmlElement):
Css.VirtualElements virtuals=element.Style.Computed.Virtuals;

Note that it's null if there aren't any.

The priority value

You'll notice that the virtuals set uses those arbitrary priority values. In order to obtain a particular virtual element, you'll need to know what its priority is - fortunately, they're constant for any given type of element:

Virtual Element	Priority (C# const)
Horizontal scrollbar	ComputedStyle.HorizontalScrollPriority
Vertical scrollbar	ComputedStyle.VerticalScrollPriority
::before	BeforeSelector.Priority
::after	AfterSelector.Priority
::marker	MarkerSelector.Priority